Process of obtaining aluminium fluorid.



' other form and Wren s'ra rns rarnur enric CHARLES A. DOREMUSQ or new rank, n. Y.

YROCESS OF OIBTBI-NING ALUMINIUM FLUOR-ID.

Llllhtfifi. No Drawing.

To (Ill whole it may concern Be it known that L'Cnannns A. Doiznnus, a citizen of the United States, residing in the county, city, and State of New York,

have invented, a new and liseful Improve-- taining aluminium fluorid from its solutions, and its object is to produce pure aluminium fluorid in solid form.

During the evaporation ofa solution of aluminium fiuorid, crystals of fluorid separate, containing water of crystallization. Their composition may be represented by the formula Al F 71BX 0. They are practically insoluble in water. If the fluoridsolution be cooled to the freezing point of water, the separating crystals will'be of ancomposition. In water these will be quite soluble,

18H O. Upon applying heat these crystals to the air or to heat,

' will lose part of the Water of crystallization.

ture.

The resulting product is insoluble i i-water. In working my improved process, I depart completely from all existing methods.

minium fiuorid, thus preventing and evaporation, and thereby obtain solid aluminium fluorid, which, under any of the conditions hereinafter stated, is practically insoluble, even in boiling water.

5 1 have found that the amount of water of :li'ystallization in the product varies with the temperature at which such product is' formed, and also, since the vessel is closed, that the pressure varies with the tempera- Thus, if the aluminium fiuorid solution in such vessel be heated to 115 (3., the

steam age will show about ten pounds pressure, the the composition of the resulting crystals mag be represented by the formula. A1 F 7H But if the solution be heated to a temperature of 121 0., when the gage will show a pressure of about fifteen pounds, the product will contain less water of crystallization than in the preceding instance, the'crystals will be of a difierent shape, and their composition may be represented by the formula A1 1 51-1 0. The latter crystals are practically insoluble, even in boiling water. And if temperatures still higher relates to the process of ob-.

and their composition may be represented by the formula Al F In a closed vessel I'heat the solution of alu Specification of Letters Patent Patented Sept. 15, Mr its. Application filed April 2, 1914. Serial No. 829,014.

than. those last mentioned are used, with correspondingly higher pressures, proporbe found in the product than appears in the above specified instances.

-Although the solution of llllllliililllll). fluorid be impure, a purified product. as in other crystallizations, will result, the for eign substancesremainin in the mother liquor. Thus if ferrous 'l'lliorid he present, it remains in solution. There is a possibility, if the elements therefor be present, of the formation of double salts, but the usual result is as stated.

In carrying out my improved process, 1 proceed as follows; Intoa suitable pressure kettle, or autoclave, which is providedd with a stirrer, I introduce the aluminium fiuorid solution, having a specific gravity 'of 1150 or higher. The solution is-then suitably heated, as by the application thereto of steam, which is let into a jacket at the bot tom" of the autoclave. When the solution has become boiling hot, the valves of then autoclave are closed, and the pressure raised to ten pounds on the steam gage. This pressure is to be maintained for several hours, at the end of which there will have been produced in the autoclave, a magma of crystals, which may then'be discharged and the crystals separated from the mother liquor, either by settling, filtration, centrifw gation, or, by any other of the well known separating de r lees. The crystals may then be washed with water and, collected. The specific gravity of the mother-liquor will be quite low and vary with cirr'zurnstanoes. A fair-example is 1050 or lower. lf'the original solution be high in impurities, the specific gravity of the mother-liquor will be high. 1

As stated above, the aluminium fluorid crystals will be free from iron salts, especially if the iron in the solution was present as ferrous fluorid. Iii, such case the resultingcrystals will be [of the formula Al F 7H O. But if the solution is heated till the gage shows a pressure of about fifteen pounds, the composition will be ALF 5H1).

T he separation from iron is the same as in the case of the other crystals. ln cachinstance the separation of impurities takes place in the manner above described, independently of hydration of the crystals.

ticnately less \vatcg' of crystallizathvu will What 1 cl i m as new, and desire to secure by Letters 7 v I 1. The process of btaining aluminium fiuorid .from its solutions, which consists in the application of heat to said solution conatent, is:

tained in a closed vessel. substantially as described.

.in a closed vessel, a solution of such alu- V minium fluorid, the proportion of water of crystallization diminishing according as the temperature applied is raised, substantially as described. g 15 3. The process of obtaining hydrous alu minjium' fiuorid in crystalline form, which consists in heating, in a closed vessel, a solution' of aluminium 'fluorid, and stirring the same while heating continues, substantially 20 as described.

CHARLES A. DOR'EMUS.

Y Witnesses: I

WM. S. BEAMAN, CHARLES B. MEYER. 

